diff --git a/fcore/rect.sml b/fcore/rect.sml
index f973ff4..6f3bbba 100644
--- a/fcore/rect.sml
+++ b/fcore/rect.sml
@@ -1,27 +1,35 @@
-structure Rect =
+structure Rect = 
 struct
-  fun lerp (startX, startY, drawWidth, drawHeight, windowWidth, windowHeight, r, g, b) : Real32.real vector =
+  fun xToNdc (xOffset, xpos, scale, halfWidth) =
+    ((xpos * scale + xOffset) - halfWidth) / halfWidth
+
+  fun yToNdc (yOffset, ypos, scale, halfHeight) =
+   ~(((ypos * scale + yOffset) - halfHeight) / halfHeight)
+
+  fun lerp (xOffset: Real32.real, yOffset, scale, windowWidth, windowHeight, r, g, b) =
     let
-       val startX = Real32.fromInt startX
-       val startY = Real32.fromInt startY
-       val endY = windowHeight - startY
-       val startY = windowHeight - (startY + drawHeight)
-       val endX = startX + drawWidth
-       val windowHeight = windowHeight / 2.0
-       val windowWidth = windowWidth / 2.0
+      val halfWidth = windowWidth / 2.0
+      val halfHeight = windowHeight / 2.0
     in
-       #[      (((startX * (1.0 - 0.733333349228)) + (endX * 0.733333349228)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 1.0)) + (endY * 1.0)) / windowHeight) - 1.0, r, g, b,
-      (((startX * (1.0 - 0.733333349228)) + (endX * 0.733333349228)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 0.0)) + (endY * 0.0)) / windowHeight) - 1.0, r, g, b,
-      (((startX * (1.0 - 0.266666650772)) + (endX * 0.266666650772)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 0.0)) + (endY * 0.0)) / windowHeight) - 1.0, r, g, b,
-      (((startX * (1.0 - 0.266666650772)) + (endX * 0.266666650772)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 0.0)) + (endY * 0.0)) / windowHeight) - 1.0, r, g, b,
-      (((startX * (1.0 - 0.266666650772)) + (endX * 0.266666650772)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 1.0)) + (endY * 1.0)) / windowHeight) - 1.0, r, g, b,
-      (((startX * (1.0 - 0.733333349228)) + (endX * 0.733333349228)) / windowWidth) - 1.0,
-      (((startY * (1.0 - 1.0)) + (endY * 1.0)) / windowHeight) - 1.0, r, g, b
-    ]
-  end
+     #[
+xToNdc (xOffset, 0.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 13.000000000000000, scale, halfHeight),
+r, g, b,
+xToNdc (xOffset, 6.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 13.000000000000000, scale, halfHeight),
+r, g, b,
+xToNdc (xOffset, 0.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 0.000000000000000, scale, halfHeight),
+r, g, b,
+xToNdc (xOffset, 0.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 0.000000000000000, scale, halfHeight),
+r, g, b,
+xToNdc (xOffset, 6.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 13.000000000000000, scale, halfHeight),
+r, g, b,
+xToNdc (xOffset, 6.000000000000000, scale, halfWidth),
+yToNdc (yOffset, 0.000000000000000, scale, halfHeight),
+r, g, b
+      ]
+    end
 end
diff --git a/fcore/text-builder.sml b/fcore/text-builder.sml
index 1a65883..fd385b7 100644
--- a/fcore/text-builder.sml
+++ b/fcore/text-builder.sml
@@ -71,6 +71,10 @@ struct
   (* same as buildTextStringAfterCursor, except this keeps track of absolute
    * index and cursor pos too *)
 
+  fun makeRect (posX, posY, fw, fh, r, g, b) =
+    Rect.lerp
+      (Real32.fromInt (posX - 1), Real32.fromInt posY, scale, fw, fh, r, g, b)
+
   fun makeChr (chr, posX, posY, windowWidth, windowHeight, r, g, b) =
     CozetteAscii.make
       ( chr
@@ -124,8 +128,7 @@ struct
             let
               val {r, g, b, fw, fh, ...} = env
 
-              val cursorAcc = Rect.lerp
-                (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+              val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
             in
               buildTextString
                 ( pos + 1
@@ -165,8 +168,7 @@ struct
               let
                 val {r, g, b, fw, fh, ...} = env
 
-                val cursorAcc = Rect.lerp
-                  (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
               in
                 buildTextString
                   ( pos + 1
@@ -241,8 +243,7 @@ struct
               let
                 val {fw, fh, r, g, b, hr, hg, hb, ...} = env
 
-                val cursorAcc = Rect.lerp
-                  (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
               in
                 if posX + xSpace < #w env then
                   let
@@ -372,8 +373,7 @@ struct
                 val b: Real32.real = 0.1
                 val {fw, fh, ...} = env
 
-                val space = Rect.lerp
-                  (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                val space = makeRect (posX, posY, fw, fh, r, g, b)
                 val bgAcc = space :: bgAcc
               in
                 buildTextStringSearch
@@ -417,8 +417,7 @@ struct
             let
               val {fw, fh, r, g, b, ...} = env
 
-              val cursorAcc = Rect.lerp
-                (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+              val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
             in
               buildTextStringSearch
                 ( pos + 1
@@ -464,8 +463,7 @@ struct
               let
                 val {fw, fh, r, g, b, ...} = env
 
-                val cursorAcc = Rect.lerp
-                  (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
               in
                 buildTextStringSearch
                   ( pos + 1
@@ -512,8 +510,7 @@ struct
                     val g: Real32.real = 0.1
                     val b: Real32.real = 0.1
 
-                    val space = Rect.lerp
-                      (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                    val space = makeRect (posX, posY, fw, fh, r, g, b)
                     val bgAcc = space :: bgAcc
                   in
                     buildTextStringSearch
@@ -597,8 +594,7 @@ struct
               (* equal to cursor *)
               let
                 val {fw, fh, r, g, b, hr, hg, hb, ...} = env
-                val cursorAcc = Rect.lerp
-                  (posX, posY, fontSize, fontSize, fw, fh, r, g, b)
+                val cursorAcc = makeRect (posX, posY, fw, fh, r, g, b)
               in
                 if posX + xSpace < #w env then
                   let